Nineteenth-century writers in the United States, whether they wrote novels, short stories, poems or plays, were powerfully drawn to the railroad in its golden years. In fact, writers responded to the railroads as soon as the first were built in the 1830's. By the 1850's, the railroad was a major presence in the life of the nation. Writers such as Ralph Waldo Emerson and Henry David saw the railroad both as a boon  to democracy  and as an object of suspicion. The railroad could be and was a despoiler  of nature, furthermore, in its manifestation of speed and noise. _ might be a despoiler of human nature as well. By the 1850's and 1860's, there was a great distrust among writer and intellectuals of the rapid industrialization of which the railroad was a leading force. Deeply philosophical historians such as Henry Adams lamented the role that the new frenzy for business was playing in eroding traditional values. A distrust of industry and business continued among writers throughout the rest of the nineteenth century and into the twentieth. For the most part, the literature in which the railroad plays and important role belong to popular culture rather than to the realm of serious art. One thinks of melodramas, boys' books, thrillers, romances, and the like rather than novels of the _ . In the railroads' prime years, between 1890 and 1920, there were a few individuals in the United States, most of them with solid railroading experience behind them, who made a profession of writing about railroading--works offering the ambience of stations, yards, and locomotive cabs. These writers, who can genuinely be said to have created a genre, the "railroad novel", are now mostly forgotten, their names having faded from memory. But anyone who takes the time to consult their fertile writings will still find a treasure trove of information about the place of the railroad in the life of the United States. According to the passage, the railroad played a significant role in literature in all of the following kinds of books except  _  . A) thrillers B) boys' books C) romances D) important novels
D

In the near future, people in some parts of the world will watch a new kind of television. It is called the high definition television or the HD-TV. The main difference between an HD-TV and a normal television is the picture. It is more clear and detailed. This is because the HD-TV has many more points and lines that make a television image. Every color television picture contains thousands of red, green and blue points. They all come together as an image in the eye of the person watching. The points are organized in lines that go across the television screen. There are more than five hundred lines in a normal television. The HD-TV has two times as many. To get this clear picture, you must have a big screen. Experts say people using a small screen will see little difference. The HD-TV also has clear sound. It is like the sound on a CD. All these improvements make an HD-TV very costly. One kind in Japan now sells for more than twenty thousand dollars .A major problem with the HD-TV is its broadcast signal(.The signal is bigger than normal because it carries more electronic information. How many lines does an HD-TV have? A) Over 250 B) More than 500 C) More than 1,000 D) About 250
C

A breathtaking trick potentially left over from our ancestors might be found in us -- the ability to sense oxygen through our skin. Amphibians, animals such as frogs that can live both on land and in water, have long been known to be capable of breathing through their skin. In fact, the first known lungless frog that breathes only through its skin was discovered recently in the rivers of Borneo. Now the same oxygen sensors found in frog skins and in the lungs of mammals   have unexpectedly been discovered in the skin of mice. "No one had ever looked," explained Randall Johnson, a biologist researcher. Mice and frogs are quite distant relatives, so the fact they have these molecules   in common in their skin suggests they might well be found in the skin of other mammals, such as humans. "We have no reason to think that they are not in the skin of people too," Johnson said. These molecules not only detect oxygen, but help increase levels of vital red blood cells, which carry oxygen around the body. Normal mice breathing in air that is 10 percent oxygen--a dangerously low level similar to conditions at the top of Mount Everest, and about half that of air at sea level. However, mice that had the oxygen sensor HIF-1a genetically removed from their skin failed to produce this hormone   even after hours of such low oxygen. These findings, if they hold true in humans, suggest one could raise the level of oxygen circulating inside the body. This could help treat lung diseases and disorders such as anemia   without injecting drugs, which make up a multibillion-dollar market, Johnson said. Athletes also often try to get more oxygen delivered to their muscles in order to improve their performance. They often do this by training at high altitudes or in low-oxygen tents. The new study suggests they might want to expose their skin as well as breathing in low-oxygen air to improve their performance. "It's hard to say what exactly might be done, however--there's a lot we don't know yet," Johnson explained. The scientists... The best title of the passage may be   _  . A) Humans Might Sense Oxygen Through Skin B) Frogs And Mice Are Distant Relatives C) First Known Animal Breathes Through Skin D) Great Findings Benefits Athletes A Lot
A

Upon reaching an appropriate age (usually between 18 and 21 years), children are encouraged, but not forced, to "leave the nest" and begin an independent life. After children leave home, they often find social relationship and financial support outside the family. Parents do not arrange marriages for their children, nor do children usually ask permission of their parents to get married. Romantic love is most often the basis for marriage in the United States; young adults meet their future spouses through other friends, at jobs,  and in organizations and religious institutions. Although children choose their own spouses, they still hope their parents will approve of their choices. In many families, parents feel that children should make major life decisions by themselves. A parent may try to influence a child to follow a particular profession but the child is free to choose another career. Sometimes children do exactly the opposite of what their parents wish in order to be independent. A son may decide not to go into his father's business on purpose because of a fear that he will lose his autonomy  in his father's workplace. This independence from parents is not an indication that parents and children do not love each other. Strong love between parents and children is universal and this is no exception in the American family. Coexisting with such love in the American family are cultural values of self-reliance and independence. The writer discusses the marriage of young adults in order to show which of the following? A) They have independence. B) They want to win the permission of their parents. C) They enjoy the freedom of choosing their spouses. D) They want to challenge the authority of their parents.

A